The specific interactions of the pairs laminin binding protein (LBP)-purified tick-borne encephalitis viral surface protein E and certain recombinant fragments of this protein, as well as West Nile viral surface protein E and certain recombinant fragments of that protein, are studied by combined methods of single-molecule dynamic force spectroscopy (SMDFS), enzyme immunoassay and optical surface waves-based biosensor measurements. The experiments were performed at neutral pH (7.4) and acid pH (5.3) conditions. The data obtained confirm the role of LBP as a cell receptor for two typical viral species of the Flavivirus genus. A comparison of these data with similar data obtained for another cell receptor of this family, namely human αVβ3 integrin, reveals that both these receptors are very important. Studying the specific interaction between the cell receptors in question and specially prepared monoclonal antibodies against them, we could show that both interaction sites involved in the process of virus-cell interaction remain intact at pH 5.3. At the same time, for these acid conditions characteristic for an endosome during flavivirus-cell membrane fusion, SMDFS data reveal the existence of a force-induced (effective already for forces as small as 30-70 pN) sharp globule-coil transition for LBP and LBP-fragments of protein E complexes. We argue that this conformational transformation, being an analog of abrupt first-order phase transition and having similarity with the famous Rayleigh hydrodynamic instability, might be indispensable for the flavivirus-cell membrane fusion process.

The BstF5I restriction-modification system from Bacillus stearothermophilus F5 includes four site-specific DNA methyltransferases, thus differing from all known restriction-modification systems. Here we demonstrated for the first time that one bacterial cell can possess two pairs of methylases with identical substrate specificities (methylases BstF5I-1 and BstF5I-3 recognize GGATG, whereas methylases BstF5I-2 and BstF5I-4 recognize CATCC) that modify adenine residues on both DNA strands. Different chromatographic methods provide homogenous preparations of methylases BstF5I-2 and BstF5I-4. We estimated the principal kinetic parameters of the reaction of transfer of methyl group from the donor S-adenosyl-L-methionine to the recognition site 5;-CATCC-3; catalyzed by BstF5I-2 and BstF5I-4 DNA [N6-adenine]-methyltransferases from the BstF5I restriction-modification system.

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Hypermethylation of the RcgY sites is shown for many cancer diseases. such aberrant methylation, suppressing the gene activity, occurs at early stages of carcinogenesis. Recently, using glad-pcR assay, we have detected aberrantly methylated RcgY sites, which can be considered to be epigenetic markers of colorectal, lung, and gastric cancers. in breast cancer, methylation of the regulatory regions of ALX4, BMP2, CCND2, CDH13, CDX1, FOXA1, GALR1, GATA5, GREM1, HIC1, HMX2, HS3ST2, HOXC10, ICAM5, LAMA1, RARB, RASSF1A, RUNX3, RXRG, RYR2, SFRP2, SOX17, TERT, and ZNF613 tumor-suppressor genes is reported. in the present work, we determined aberrantly methylated RcgY sites in the regulatory regions of these genes in dNa preparations from breast cancer tissues. the study of dNa samples from 30 tumor and 22 normal mammary tissue samples demonstrates a high diagnostic potential of selected R(5mc)gY sites in regulatory regions of CCND2, BMP2, GALR1, SOX17, HMX2, and HS3ST2 genes with total index of sensitivity and specificity for R(5mc)gY detection in tumor dNa 90.0 % and 100.0 %, respectively.